Optical lens set

ABSTRACT

An optical lens assembly includes a first lens of a concave image surface near its periphery, a second lens of a plastic material, a third lens of a concave object surface near the optical-axis and a concave image surface near its periphery, a fourth lens of a concave object surface near the optical-axis, a fifth lens of a concave object surface near its periphery and a convex image surface near the optical-axis.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Chinese patent application No.201610755720.8, filed on Aug. 29, 2016, the contents of which are herebyincorporated by reference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an optical imaging lens set.Specifically speaking, the present invention is directed to an opticalimaging lens set of five lens elements for use in mobile phones, incameras, in tablet personal computers, or in personal digital assistants(PDA).

2. Description of the Prior Art

In recent years, the popularity of mobile phones and digital camerasmakes the specifications of various portable electronic products improvequickly, and so does the key component—the optical imaging lens set.However, good and necessary optical properties for taking pictures orrecording videos are not enough. There is still a need for telescopicfunction.

With the development of image sensors, the demands for the imagingquality are getting higher and higher. The conventional size of thetelescopic optical imaging lens set is longer than 50 mm and Fno numberis over 4. They fail to meet the demands for the specification ofcurrent portable electronic products. Accordingly, an optical imaginglens set of telescopic function which has improved imaging quality withreduced lens set size is still needed.

SUMMARY OF THE INVENTION

In light of the above, the present invention proposes an optical imaginglens set which has a reduced optical imaging lens system length andkeeps sufficient optical performance. The optical imaging lens set offive lens elements of the present invention from an object side towardan image side in order along an optical axis has a first lens element, asecond lens element, a third lens element, a fourth lens element and afifth lens element. Each lens element has an object-side surface facingtoward an object side as well as an image-side surface facing toward animage side. The optical imaging lens set exclusively has the first lenselement, the second lens element, the third lens element, the fourthlens element and the fifth lens element with refractive power.

The first lens element has an image-side surface with a concave portionin a vicinity of its periphery. The second lens element is of a plasticmaterial. The third lens element has an object-side surface with aconcave portion in a vicinity of the optical-axis and an image-sidesurface with a concave portion in a vicinity of its periphery. Thefourth lens element has an object-side surface with a concave portion ina vicinity of the optical-axis. The fifth lens element has anobject-side surface with a concave portion in a vicinity of itsperiphery and an image-side surface with a convex portion in a vicinityof the optical-axis.

In the optical imaging lens set of five lens elements of the presentinvention, TTL is a distance from the first object-side surface to animage plane and the second lens element has a second lens elementthickness T₂ to satisfy 10.50≤TTL/T₂≤22.80.

In the optical imaging lens set of five lens elements of the presentinvention, ALT is the total thickness of all five lens elements, an airgap G₁₂ between the first lens element and the second lens element alongthe optical axis and an air gap G₄₅ between the fourth lens element andthe fifth lens element along the optical axis to satisfy5.50≤ALT/(G₁₂+G₄₅).

The optical imaging lens set of five lens elements of the presentinvention satisfies 6.50≤ALT/T₂.

In the optical imaging lens set of five lens elements of the presentinvention, an air gap G₂₃ between the second lens element and the thirdlens element along the optical axis satisfies 4.20≤TTL/(G₁₂+G₂₃+G₄₅).

In the optical imaging lens set of five lens elements of the presentinvention, the fourth lens element has a fourth lens element thicknessT₄ to satisfy ALT/T₄≤8.60.

The optical imaging lens set of five lens elements of the presentinvention satisfies 4.20≤TTL/(G₂₃+G₄₅)≤8.50.

In the optical imaging lens set of five lens elements of the presentinvention, EFL is the effective focal length of the optical imaging lensset to satisfy EFL/(G₁₂+G₂₃)≤12.70.

In the optical imaging lens set of five lens elements of the presentinvention, the fifth lens element has a fifth lens element thickness T₅to satisfy TTL/(T₄+T₅)≤6.50.

The optical imaging lens set of five lens elements of the presentinvention satisfies EFL/(G₂₃+G₄₅)≤8.6.

In the optical imaging lens set of five lens elements of the presentinvention, the third lens element has a third lens element thickness T₃to satisfy 4.20≤ALT/(T₂+T₃).

In the optical imaging lens set of five lens elements of the presentinvention, the first lens element has a first lens element thickness T₁to satisfy 2.80≤(T₁+T₄)/T₂≤4.50.

The optical imaging lens set of five lens elements of the presentinvention satisfies EFL/(G₁₂+G₂₃+G₄₅)≤10.50.

In the optical imaging lens set of five lens elements of the presentinvention, an air gap G₃₄ between the third lens element and the fourthlens element along the optical axis satisfies 1.3≤ALT/G₃₄.

The optical imaging lens set of five lens elements of the presentinvention satisfies 8.50≤EFL/T₅≤11.80.

The optical imaging lens set of five lens elements of the presentinvention satisfies 3.70≤EFL/G₃₄≤12.50.

The optical imaging lens set of five lens elements of the presentinvention satisfies 4.00≤TTL/(T₁+T₂).

The optical imaging lens set of five lens elements of the presentinvention satisfies 3.20≤TTL/(G₁₂+G₃₄).

The optical imaging lens set of five lens elements of the presentinvention satisfies 9.50≤EFL/(T₂+T₄).

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 illustrates the methods for determining the surface shapes andfor determining one region is a region in a vicinity of the optical axisor the region in a vicinity of its circular periphery of one lenselement.

FIG. 6 illustrates a first example of the optical imaging lens set ofthe present invention.

FIG. 7A illustrates the longitudinal spherical aberration on the imageplane of the first example.

FIG. 7B illustrates the astigmatic aberration on the sagittal directionof the first example.

FIG. 7C illustrates the astigmatic aberration on the tangentialdirection of the first example.

FIG. 7D illustrates the distortion aberration of the first example.

FIG. 8 illustrates a second example of the optical imaging lens set offive lens elements of the present invention.

FIG. 9A illustrates the longitudinal spherical aberration on the imageplane of the second example.

FIG. 9B illustrates the astigmatic aberration on the sagittal directionof the second example.

FIG. 9C illustrates the astigmatic aberration on the tangentialdirection of the second example.

FIG. 9D illustrates the distortion aberration of the second example.

FIG. 10 illustrates a third example of the optical imaging lens set offive lens elements of the present invention.

FIG. 11A illustrates the longitudinal spherical aberration on the imageplane of the third example.

FIG. 11B illustrates the astigmatic aberration on the sagittal directionof the third example.

FIG. 11C illustrates the astigmatic aberration on the tangentialdirection of the third example.

FIG. 11D illustrates the distortion aberration of the third example.

FIG. 12 illustrates a fourth example of the optical imaging lens set offive lens elements of the present invention.

FIG. 13A illustrates the longitudinal spherical aberration on the imageplane of the fourth example.

FIG. 13B illustrates the astigmatic aberration on the sagittal directionof the fourth example.

FIG. 13C illustrates the astigmatic aberration on the tangentialdirection of the fourth example.

FIG. 13D illustrates the distortion aberration of the fourth example.

FIG. 14 illustrates a fifth example of the optical imaging lens set offive lens elements of the present invention.

FIG. 15A illustrates the longitudinal spherical aberration on the imageplane of the fifth example.

FIG. 15B illustrates the astigmatic aberration on the sagittal directionof the fifth example.

FIG. 15C illustrates the astigmatic aberration on the tangentialdirection of the fifth example.

FIG. 15D illustrates the distortion aberration of the fifth example.

FIG. 16 illustrates a sixth example of the optical imaging lens set offive lens elements of the present invention.

FIG. 17A illustrates the longitudinal spherical aberration on the imageplane of the sixth example.

FIG. 17B illustrates the astigmatic aberration on the sagittal directionof the sixth example.

FIG. 17C illustrates the astigmatic aberration on the tangentialdirection of the sixth example.

FIG. 17D illustrates the distortion aberration of the sixth example.

FIG. 18 illustrates a seventh example of the optical imaging lens set offive lens elements of the present invention.

FIG. 19A illustrates the longitudinal spherical aberration on the imageplane of the seventh example.

FIG. 19B illustrates the astigmatic aberration on the sagittal directionof the seventh example.

FIG. 19C illustrates the astigmatic aberration on the tangentialdirection of the seventh example.

FIG. 19D illustrates the distortion aberration of the seventh example.

FIG. 20 illustrates an eighth example of the optical imaging lens set offive lens elements of the present invention.

FIG. 21A illustrates the longitudinal spherical aberration on the imageplane of the eighth example.

FIG. 21B illustrates the astigmatic aberration on the sagittal directionof the eighth example.

FIG. 21C illustrates the astigmatic aberration on the tangentialdirection of the eighth example.

FIG. 21D illustrates the distortion aberration of the eighth example.

FIG. 22 illustrates a ninth example of the optical imaging lens set offive lens elements of the present invention.

FIG. 23A illustrates the longitudinal spherical aberration on the imageplane of the ninth example.

FIG. 23B illustrates the astigmatic aberration on the sagittal directionof the ninth example.

FIG. 23C illustrates the astigmatic aberration on the tangentialdirection of the ninth example.

FIG. 23D illustrates the distortion aberration of the ninth example.

FIG. 24 shows the optical data of the first example of the opticalimaging lens set.

FIG. 25 shows the aspheric surface data of the first example.

FIG. 26 shows the optical data of the second example of the opticalimaging lens set.

FIG. 27 shows the aspheric surface data of the second example.

FIG. 28 shows the optical data of the third example of the opticalimaging lens set.

FIG. 29 shows the aspheric surface data of the third example.

FIG. 30 shows the optical data of the fourth example of the opticalimaging lens set.

FIG. 31 shows the aspheric surface data of the fourth example.

FIG. 32 shows the optical data of the fifth example of the opticalimaging lens set.

FIG. 33 shows the aspheric surface data of the fifth example.

FIG. 34 shows the optical data of the sixth example of the opticalimaging lens set.

FIG. 35 shows the aspheric surface data of the sixth example.

FIG. 36 shows the optical data of the seventh example of the opticalimaging lens set.

FIG. 37 shows the aspheric surface data of the seventh example.

FIG. 38 shows the optical data of the eighth example of the opticalimaging lens set.

FIG. 39 shows the aspheric surface data of the eighth example.

FIG. 40 shows the optical data of the ninth example of the opticalimaging lens set.

FIG. 41 shows the aspheric surface data of the ninth example.

FIG. 42 shows some important ratios in the examples.

DETAILED DESCRIPTION

Before the detailed description of the present invention, the firstthing to be noticed is that in the present invention, similar (notnecessarily identical) elements are labeled as the same numeralreferences. In the entire present specification, “a certain lens elementhas negative/positive refractive power” refers to the part in a vicinityof the optical axis of the lens element has negative/positive refractivepower calculated by Gaussian optical theory. An object-side/image-sidesurface refers to the region which allows imaging light passing through,in the drawing, imaging light includes Lc (chief ray) and Lm (marginalray). As shown in FIG. 1, the optical axis is “I” and the lens elementis symmetrical with respect to the optical axis I. The region A thatnear the optical axis and for light to pass through is the region in avicinity of the optical axis, and the region C that the marginal raypassing through is the region in a vicinity of a certain lens element'scircular periphery. In addition, the lens element may include anextension part E for the lens element to be installed in an opticalimaging lens set (that is the region outside the region C perpendicularto the optical axis). Ideally speaking, no light would pass through theextension part, and the actual structure and shape of the extension partis not limited to this and may have other variations. For the reason ofsimplicity, the extension part is not illustrated in the followingexamples. More, precisely, the method for determining the surface shapesor the region in a vicinity of the optical axis, the region in avicinity of its circular periphery and other regions is described in thefollowing paragraphs:

-   1. FIG. 1 is a radial cross-sectional view of a lens element. Before    determining boundaries of those aforesaid portions, two referential    points should be defined first, middle point and conversion point.    The middle point of a surface of a lens element is a point of    intersection of that surface and the optical axis. The conversion    point is a point on a surface of a lens element, where the tangent    line of that point is perpendicular to the optical axis.    Additionally, if multiple conversion points appear on one single    surface, then these conversion points are sequentially named along    the radial direction of the surface with numbers starting from the    first conversion point. For instance, the first conversion point    (closest one to the optical axis), the second conversion point, and    the N^(th) conversion point (farthest one to the optical axis within    the scope of the clear aperture of the surface). The portion of a    surface of the lens element between the middle point and the first    conversion point is defined as the portion in a vicinity of the    optical axis. The portion located radially outside of the N^(th)    conversion point (but still within the scope of the clear aperture)    is defined as the portion in a vicinity of a periphery of the lens    element. In some embodiments, there are other portions existing    between the portion in a vicinity of the optical axis and the    portion in a vicinity of a periphery of the lens element; the    numbers of portions depend on the numbers of the conversion    point(s). In addition, the radius of the clear aperture (or a    so-called effective radius) of a surface is defined as the radial    distance from the optical axis I to a point of intersection of the    marginal ray Lm and the surface of the lens element.-   2. Referring to FIG. 2, determining the shape of a portion is convex    or concave depends on whether a collimated ray passing through that    portion converges or diverges. That is, while applying a collimated    ray to a portion to be determined in terms of shape, the collimated    ray passing through that portion will be bended and the ray itself    or its extension line will eventually meet the optical axis. The    shape of that portion can be determined by whether the ray or its    extension line meets (intersects) the optical axis (focal point) at    the object-side or image-side. For instance, if the ray itself    intersects the optical axis at the image side of the lens element    after passing through a portion, i.e. the focal point of this ray is    at the image side (see point R in FIG. 2), the portion will be    determined as having a convex shape. On the contrary, if the ray    diverges after passing through a portion, the extension line of the    ray intersects the optical axis at the object side of the lens    element, i.e. the focal point of the ray is at the object side (see    point M in FIG. 2), that portion will be determined as having a    concave shape. Therefore, referring to FIG. 2, the portion between    the middle point and the first conversion point has a convex shape,    the portion located radially outside of the first conversion point    has a concave shape, and the first conversion point is the point    where the portion having a convex shape changes to the portion    having a concave shape, namely the border of two adjacent portions.    Alternatively, there is another common way for a person with    ordinary skill in the art to tell whether a portion in a vicinity of    the optical axis has a convex or concave shape by referring to the    sign of an “R” value, which is the (paraxial) radius of curvature of    a lens surface. The R value is commonly used in conventional optical    design software such as Zemax and CodeV. The R value usually appears    in the lens data sheet in the software. For an object-side surface,    positive R means that the object-side surface is convex, and    negative R means that the object-side surface is concave.    Conversely, for an image-side surface, positive R means that the    image-side surface is concave, and negative R means that the    image-side surface is convex. The result found by using this method    should be consistent as by using the other way mentioned above,    which determines surface shapes by referring to whether the focal    point of a collimated ray is at the object side or the image side.-   3. For none conversion point cases, the portion in a vicinity of the    optical axis is defined as the portion between 0˜50% of the    effective radius (radius of the clear aperture) of the surface,    whereas the portion in a vicinity of a periphery of the lens element    is defined as the portion between 50˜100% of effective radius    (radius of the clear aperture) of the surface.

Referring to the first example depicted in FIG. 3, only one conversionpoint, namely a first conversion point, appears within the clearaperture of the image-side surface of the lens element. Portion I is aportion in a vicinity of the optical axis, and portion II is a portionin a vicinity of a periphery of the lens element. The portion in avicinity of the optical axis is determined as having a concave surfacedue to the R value at the image-side surface of the lens element ispositive. The shape of the portion in a vicinity of a periphery of thelens element is different from that of the radially inner adjacentportion, i.e. the shape of the portion in a vicinity of a periphery ofthe lens element is different from the shape of the portion in avicinity of the optical axis; the portion in a vicinity of a peripheryof the lens element has a convex shape.

Referring to the second example depicted in FIG. 4, a first conversionpoint and a second conversion point exist on the object-side surface(within the clear aperture) of a lens element. In which portion I is theportion in a vicinity of the optical axis, and portion III is theportion in a vicinity of a periphery of the lens element. The portion ina vicinity of the optical axis has a convex shape because the R value atthe object-side surface of the lens element is positive. The portion ina vicinity of a periphery of the lens element (portion III) has a convexshape. What is more, there is another portion having a concave shapeexisting between the first and second conversion point (portion II).

Referring to a third example depicted in FIG. 5, no conversion pointexists on the object-side surface of the lens element. In this case, theportion between 0˜50% of the effective radius (radius of the clearaperture) is determined as the portion in a vicinity of the opticalaxis, and the portion between 50˜100% of the effective radius isdetermined as the portion in a vicinity of a periphery of the lenselement. The portion in a vicinity of the optical axis of theobject-side surface of the lens element is determined as having a convexshape due to its positive R value, and the portion in a vicinity of aperiphery of the lens element is determined as having a convex shape aswell.

As shown in FIG. 6, the optical imaging lens set 1 of five lens elementsof the present invention, sequentially located from an object side 2(where an object is located) to an image side 3 along an optical axis 4,has an aperture stop (ape. stop) 80, a first lens element 10, a secondlens element 20, a third lens element 30, a fourth lens element 40, afifth lens element 50, a filter 70 and an image plane 71. Generallyspeaking, the first lens element 10, the second lens element 20, thethird lens element 30, the fourth lens element 40 and the fifth lenselement 50 may be made of a transparent plastic material but the presentinvention is not limited to this, and each lens element has anappropriate refractive power. There are exclusively five lens elements,which means the first lens element 10, the second lens element 20, thethird lens element 30, the fourth lens element 40 and the fifth lenselement 50 with refractive power in the optical imaging lens set 1 ofthe present invention. The optical axis 4 is the optical axis of theentire optical imaging lens set 1, and the optical axis of each of thelens elements coincides with the optical axis of the optical imaginglens set 1.

Furthermore, the optical imaging lens set 1 includes an aperture stop(ape. stop) 80 disposed in an appropriate position. In FIG. 6, theaperture stop 80 is disposed between the object side 2 and the firstlens element 10. When light emitted or reflected by an object (notshown) which is located at the object side 2 enters the optical imaginglens set 1 of the present invention, it forms a clear and sharp image onthe image plane 71 at the image side 3 after passing through theaperture stop 80, the first lens element 10, the second lens element 20,the third lens element 30, the fourth lens element 40, the fifth lenselement 50 and the filter 70. In one embodiments of the presentinvention, the optional filter 70 may be a filter of various suitablefunctions. For example, the filter 70 may be an infrared cut filter (IRcut filter), placed between the image-side surface 52 of the fifth lenselement 50 and the image plane 71.

Each lens element in the optical imaging lens set 1 of the presentinvention has an object-side surface facing toward the object side 2 aswell as an image-side surface facing toward the image side 3. Forexample, the first lens element 10 has a first object-side surface 11and a first image-side surface 12; the second lens element 20 has asecond object-side surface 21 and a second image-side surface 22; thethird lens element 30 has a third object-side surface 31 and a thirdimage-side surface 32; the fourth lens element 40 has a fourthobject-side surface 41 and a fourth image-side surface 42; the fifthlens element 50 has a fifth object-side surface 51 and a fifthimage-side surface 52. In addition, each object-side surface andimage-side surface in the optical imaging lens set 1 of the presentinvention has a part (or portion) in a vicinity of its circularperiphery (circular periphery part) away from the optical axis 4 as wellas a part in a vicinity of the optical axis (optical axis part) close tothe optical axis 4.

Each lens element in the optical imaging lens set 1 of the presentinvention further has a central thickness T on the optical axis 4. Forexample, the first lens element 10 has a first lens element thicknessT₁, the second lens element 20 has a second lens element thickness T₂,the third lens element 30 has a third lens element thickness T₃, thefourth lens element 40 has a fourth lens element thickness T₄, the fifthlens element 50 has a fifth lens element thickness T₅. Therefore, thetotal thickness of all the lens elements in the optical imaging lens set1 along the optical axis 4 is ALT=T₁+T₂+T₃+T₄+T₅.

In addition, between two adjacent lens elements in the optical imaginglens set 1 of the present invention there is an air gap along theoptical axis 4. For example, an air gap G₁₂ is disposed between thefirst lens element 10 and the second lens element 20, an air gap G₂₃ isdisposed between the second lens element 20 and the third lens element30, an air gap G₃₄ is disposed between the third lens element 30 and thefourth lens element 40, as well as an air gap G₄₅ is disposed betweenthe fourth lens element 40 and the fifth lens element 50. Therefore, thesum of total five air gaps between adjacent lens elements from the firstlens element 10 to the fifth lens element 50 along the optical axis 4 isAAG=G₁₂+G₂₃+G₃₄+G₄₅.

In addition, the distance between the first object-side surface 11 ofthe first lens element 10 and the image plane 71, namely the totallength of the optical imaging lens set 1, along the optical axis 4 isTTL. EFL represents the effective focal length of the optical imaginglens set 1.

Furthermore, the focal length of the first lens element 10 is f1; thefocal length of the second lens element 20 is f2; the focal length ofthe third lens element 30 is f3; the focal length of the fourth lenselement 40 is f4; the focal length of the fifth lens element 50 is f5;the refractive index of the first lens element 10 is n1; the refractiveindex of the second lens element 20 is n2; the refractive index of thethird lens element 30 is n3; the refractive index of the fourth lenselement 40 is n4; the refractive index of the fifth lens element 50 isn5; the Abbe number of the first lens element 10 is υ1; the Abbe numberof the second lens element 20 is υ2; the Abbe number of the third lenselement 30 is υ3; and the Abbe number of the fourth lens element 40 isυ4; the Abbe number of the fifth lens element 50 is υ5.

FIRST EXAMPLE

Please refer to FIG. 6 which illustrates the first example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 7A for the longitudinal spherical aberration on the image plane 71of the first example; please refer to FIG. 7B for the astigmatic fieldaberration on the sagittal direction; please refer to FIG. 7C for theastigmatic field aberration on the tangential direction, and pleaserefer to FIG. 7D for the distortion aberration. The Y axis of thespherical aberration in each example is “field of view” for 1.0. The Yaxis of the astigmatic field and the distortion in each example standsfor “image height”, which is 2.62 mm.

The optical imaging lens set 1 of the first example has five lenselements 10 to 50 with refractive power. The optical imaging lens set 1also has a filter 70, an aperture stop 80, and an image plane 71. Theaperture stop 80 is provided between the object side 2 and the firstlens element 10. The filter 70 may be used for preventing specificwavelength light (such as the infrared light) reaching the image planeto adversely affect the imaging quality.

The first lens element 10 has positive refractive power. The firstobject-side surface 11 facing toward the object side 2 has a convex part13 in the vicinity of the optical axis and a convex part 14 in avicinity of its circular periphery. The first image-side surface 12facing toward the image side 3 has a concave part 16 in the vicinity ofthe optical axis and a concave part 17 in a vicinity of its circularperiphery. Besides, both the first object-side surface 11 and the firstimage-side 12 of the first lens element 10 are aspherical surfaces.

The second lens element 20 is of a plastic material and has negativerefractive power. The second object-side surface 21 facing toward theobject side 2 has a convex part 23 in the vicinity of the optical axisand a convex part 24 in a vicinity of its circular periphery. The secondimage-side surface 22 facing toward the image side 3 has a concave part26 in the vicinity of the optical axis and a concave part 27 in avicinity of its circular periphery. Both the second object-side surface21 and the second image-side 22 of the second lens element 20 areaspherical surfaces.

The third lens element 30 has positive refractive power. The thirdobject-side surface 31 facing toward the object side 2 has a concavepart 33 in the vicinity of the optical axis and a convex part 34 in avicinity of its circular periphery. The third image-side surface 32facing toward the image side 3 has a convex part 36 in the vicinity ofthe optical axis and a concave part 37 in a vicinity of its circularperiphery. Both the third object-side surface 31 and the thirdimage-side 32 of the third lens element 30 are aspherical surfaces.

The fourth lens element 40 has negative refractive power. The fourthobject-side surface 41 facing toward the object side 2 has a concavepart 43 in the vicinity of the optical axis and a concave part 44 in avicinity of its circular periphery. The fourth image-side surface 42facing toward the image side 3 has a concave part 46 in the vicinity ofthe optical axis and a convex part 47 in a vicinity of its circularperiphery. Both the fourth object-side surface 41 and the fourthimage-side 42 of the fourth lens element 40 are aspherical surfaces.

The fifth lens element 50 has positive refractive power. The fifthobject-side surface 51 facing toward the object side 2 has a concavepart 53 in the vicinity of the optical axis and a concave part 54 in avicinity of its circular periphery. The fifth image-side surface 52facing toward the image side 3 has a convex part 56 in the vicinity ofthe optical axis and a convex part 57 in a vicinity of its circularperiphery. Both the fifth object-side surface 51 and the fifthimage-side 52 of the fifth lens element 50 are aspherical surfaces.

In the first lens element 10, the second lens element 20, the third lenselement 30, the fourth lens element 40 and the fifth lens element 50 ofthe optical imaging lens element 1 of the present invention, there are10 surfaces, such as the object-side surfaces 11/21/31/41/51 and theimage-side surfaces 12/22/32/42/52. If a surface is aspherical, theseaspheric coefficients are defined according to the following formula:

${Z(Y)} = {{\frac{Y^{2}}{R}/\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}{a_{i} \times Y^{i}}}}$In which:

-   R represents the curvature radius of the lens element surface;-   Z represents the depth of an aspherical surface (the perpendicular    distance between the point of the aspherical surface at a distance Y    from the optical axis and the tangent plane of the vertex on the    optical axis of the aspherical surface);-   Y represents a vertical distance from a point on the aspherical    surface to the optical axis;-   K is a conic constant;-   a_(i) is the aspheric coefficient of the i^(th) order.

The optical data of the first example of the optical imaging lens set 1are shown in FIG. 24 while the aspheric surface data are shown in FIG.25. In the present examples of the optical imaging lens set, thef-number of the entire optical lens element system is Fno, EFL is theeffective focal length, HFOV stands for the half field of view which ishalf of the field of view of the entire optical lens element system, andthe unit for the curvature radius, the thickness and the focal length isin millimeters (mm). TTL is 6.0187 mm. Fno is 2.6614. The image heightis 2.62 mm. HFOV is 21.6855 degrees.

SECOND EXAMPLE

Please refer to FIG. 8 which illustrates the second example of theoptical imaging lens set 1 of the present invention. It is noted thatfrom the second example to the following examples, in order to simplifythe figures, only the components different from what the first examplehas, and the basic lens elements will be labeled in figures. Othercomponents that are the same as what the first example has, such as theobject-side surface, the image-side surface, the part in a vicinity ofthe optical axis and the part in a vicinity of its circular peripherywill be omitted in the following examples. Please refer to FIG. 9A forthe longitudinal spherical aberration on the image plane 71 of thesecond example, please refer to FIG. 9B for the astigmatic aberration onthe sagittal direction, please refer to FIG. 9C for the astigmaticaberration on the tangential direction, and please refer to FIG. 9D forthe distortion aberration. The components in the second example aresimilar to those in the first example, but the optical data such as thecurvature radius, the refractive power, the lens thickness, the lensfocal length, the aspheric surface or the back focal length in thisexample are different from the optical data in the first example, and inthis example, the fifth object-side surface 51 has a convex part 53′ inthe vicinity of the optical axis.

The optical data of the second example of the optical imaging lens setare shown in FIG. 26 while the aspheric surface data are shown in FIG.27. TTL is 6.1984 mm. Fno is 2.6014. The image height is 2.62 mm. HFOVis 21.5504 degrees. In particular, 1) the HFOV of the second example issmaller than that of the first example of the present invention.

THIRD EXAMPLE

Please refer to FIG. 10 which illustrates the third example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 11A for the longitudinal spherical aberration on the image plane 71of the third example; please refer to FIG. 11B for the astigmaticaberration on the sagittal direction; please refer to FIG. 11C for theastigmatic aberration on the tangential direction, and please refer toFIG. 11D for the distortion aberration. The components in the thirdexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fifth object-side surface 51 has a convex part53′ in the vicinity of the optical axis.

The optical data of the third example of the optical imaging lens setare shown in FIG. 28 while the aspheric surface data are shown in FIG.29. TTL is 6.1287 mm. Fno is 2.6744. The image height is 2.62 mm. HFOVis 21.4292 degrees. In particular, 1) the HFOV of the third example issmaller than that of the first example of the present invention.

FOURTH EXAMPLE

Please refer to FIG. 12 which illustrates the fourth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 13A for the longitudinal spherical aberration on the image plane 71of the fourth example; please refer to FIG. 13B for the astigmaticaberration on the sagittal direction; please refer to FIG. 13C for theastigmatic aberration on the tangential direction, and please refer toFIG. 13D for the distortion aberration. The components in the fourthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fifth object-side surface 51 has a convex part53′ in the vicinity of the optical axis.

The optical data of the fourth example of the optical imaging lens setare shown in FIG. 30 while the aspheric surface data are shown in FIG.31. TTL is 6.2344 mm. Fno is 2.6751. The image height is 2.62 mm. HFOVis 21.5813 degrees. In particular, 1) the HFOV of the fourth example issmaller than that of the first example of the present invention.

FIFTH EXAMPLE

Please refer to FIG. 14 which illustrates the fifth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 15A for the longitudinal spherical aberration on the image plane 71of the fifth example; please refer to FIG. 15B for the astigmaticaberration on the sagittal direction; please refer to FIG. 15C for theastigmatic aberration on the tangential direction, and please refer toFIG. 15D for the distortion aberration. The components in the fifthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fifth object-side surface 51 has a convex part53′ in the vicinity of the optical axis.

The optical data of the fifth example of the optical imaging lens setare shown in FIG. 32 while the aspheric surface data are shown in FIG.33. TTL is 6.2285 mm. Fno is 2.6750. The image height is 2.62 mm. HFOVis 21.5801 degrees. In particular, 1) the Fno of the fifth example islarger than that of the first example of the present invention, 2) theHFOV of the fifth example is smaller than that of the first example.

SIXTH EXAMPLE

Please refer to FIG. 16 which illustrates the sixth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 17A for the longitudinal spherical aberration on the image plane 71of the sixth example; please refer to FIG. 17B for the astigmaticaberration on the sagittal direction; please refer to FIG. 17C for theastigmatic aberration on the tangential direction, and please refer toFIG. 17D for the distortion aberration. The components in the sixthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fifth object-side surface 51 has a convex part53′ in the vicinity of the optical axis.

The optical data of the sixth example of the optical imaging lens setare shown in FIG. 34 while the aspheric surface data are shown in FIG.35. TTL is 6.1503 mm. Fno is 2.6030. The image height is 2.62 mm. HFOVis 21.7730 degrees. In particular, 1) the aperture stop of the sixthexample is larger than that of the first example of the presentinvention.

SEVENTH EXAMPLE

Please refer to FIG. 18 which illustrates the seventh example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 19A for the longitudinal spherical aberration on the image plane 71of the seventh example; please refer to FIG. 19B for the astigmaticaberration on the sagittal direction; please refer to FIG. 19C for theastigmatic aberration on the tangential direction, and please refer toFIG. 19D for the distortion aberration. The components in the seventhexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fourth object-side surface 41 has a convex part44′ in a vicinity of its circular periphery and the fourth image-sidesurface 42 has a convex part 46′ in the vicinity of the optical axis.

The optical data of the seventh example of the optical imaging lens setare shown in FIG. 36 while the aspheric surface data are shown in FIG.37. TTL is 6.3808 mm. Fno is 2.6051. The image height is 2.62 mm. HFOVis 22.0796 degrees. In particular, 1) the aperture stop of the sixthexample is larger than that of the first example of the presentinvention.

EIGHTH EXAMPLE

Please refer to FIG. 20 which illustrates the eighth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 21A for the longitudinal spherical aberration on the image plane 71of the eighth example; please refer to FIG. 21B for the astigmaticaberration on the sagittal direction; please refer to FIG. 21C for theastigmatic aberration on the tangential direction, and please refer toFIG. 21D for the distortion aberration. The components in the eighthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fourth image-side surface 42 has a convex part46′ in the vicinity of the optical axis.

The optical data of the eighth example of the optical imaging lens setare shown in FIG. 38 while the aspheric surface data are shown in FIG.39. TTL is 5.9812 mm. Fno is 2.5925. The image height is 2.62 mm. HFOVis 21.8230 degrees. In particular, 1) the TTL of the eighth example isshorter than that of the first example of the present invention, 2) theaperture stop of the eighth example is larger than that of the firstexample of the present invention.

NINTH EXAMPLE

Please refer to FIG. 22 which illustrates the ninth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 23A for the longitudinal spherical aberration on the image plane 71of the ninth example; please refer to FIG. 23B for the astigmaticaberration on the sagittal direction; please refer to FIG. 23C for theastigmatic aberration on the tangential direction, and please refer toFIG. 23D for the distortion aberration. The components in the ninthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the fifth lens element 50 has negative refractivepower and the fourth image-side surface 42 has a convex part 46′ in thevicinity of the optical axis.

The optical data of the ninth example of the optical imaging lens setare shown in FIG. 40 while the aspheric surface data are shown in FIG.41. TTL is 5.7772 mm. Fno is 2.5818. The image height is 2.62 mm. HFOVis 22.3974 degrees. In particular, 1) the TTL of the ninth example isshorter than that of the first example of the present invention, 2) theaperture stop of the ninth example is larger than that of the firstexample of the present invention.

Some important ratios in each example are shown in FIG. 42. The distancebetween the fifth image-side surface 52 of the fifth lens element 50 tothe image plane 71 along the optical axis 4 is BFL; the air gap betweenthe fifth lens element 50 and the filter 70 along the optical axis 4 isGSF; the thickness of the filter 70 along the optical axis 4 is TF; thedistance between the filter 70 to the image plane 71 along the opticalaxis 4 is GFP. Therefore, BFL=G5F+TF+GFP.

In the light of the above examples, the inventors observe at least thefollowing features:

-   1. The present invention proposes finely designed vicinity of the    optical axis of a lens element or finely designed vicinity of its    periphery. The first lens element has an image-side surface with a    concave portion in a vicinity of its periphery to recover light of    larger angle.-   2. The third lens element has an object-side surface with a concave    portion in a vicinity of the optical-axis and an image-side surface    with a concave portion in a vicinity of its periphery to concentrate    light effectively.-   3. The fourth lens element has an object-side surface with a concave    portion in a vicinity of the optical-axis to synergistically correct    the aberration.-   4. The fifth lens element has an object-side surface with a concave    portion in a vicinity of its periphery and an image-side surface    with a convex portion in a vicinity of the optical-axis to    synergistically decrease the length of the optical imaging lens set    and to ensure good imaging quality.

In addition, the inventors discover that there are some better ratioranges for different data according to the above various importantratios. Better ratio ranges help the designers to design a betteroptical performance and practically possible optical imaging lens set.For example:

-   1. Any one of the following conditions shows a smaller numerator    when the denominator is fixed to exhibit the decrease of the total    size:    TTL/T ₂≤22.80;    ALT/T ₄≤8.60;    TTL/(G ₂₃ +G ₄₅)≤8.50;    EFL/(G ₁₂ +G ₂₃)≤12.70;    TTL/(T ₄ +T ₅)≤6.50;    EFL/(G ₂₃ +G ₄)≤8.6;    (T ₁ +T ₄)/T ₂≤4.50;    EFL/(G ₁₂ +G ₂₃ +G ₄₅)≤10.50;    EFL/T ₅≤11.80;    EFL/G ₃₄≤12.50.

When the following conditions are further met, better imaging quality ispossible:10.50≤TTL/T ₂≤22.80;4.20≤TTL/(G ₂₃ +G ₄₅)≤8.50;2.80≤(T ₁ +T ₄)/T ₂≤4.50;8.50≤EFL/T ₅≤11.80;3.70≤EFL/G ₃₄≤12.50.

When one of the following conditions is met, it shows betterarrangements to provide better imaging quality when good yield ismaintained:5.50≤ALT/(G ₁₂ +G ₄₅);6.50≤ALT/T ₂;4.20≤TTL/(G ₁₂ +G ₂₃ +G ₄₅);4.20≤ALT/(T ₂ +T ₃);1.3≤ALT/G ₃₄;4.00≤TTL/(T ₁ +T ₂);3.20≤TTL/(G ₁₂ +G ₃₄);9.50≤EFL/(T ₂ +T ₄).

When any one of the following conditions is further met, it additionallykeeps a suitable size:5.50≤ALT/(G ₁₂ +G ₄₅)≤22.90;6.50≤ALT/T ₂≤9.50;4.20≤TTL/(G ₁₂ +G ₂₃ +G ₄₅)≤8.0;4.20≤ALT/(T ₂ +T ₃)≤4.60;1.3≤ALT/G ₃₄≤1.90 ;4.00≤TTL/(T ₁ +T ₂)≤5.80;3.20≤TTL/(G ₁₂ +G ₃₄)≤4.30;9.50≤EFL/(T ₂ +T ₄)≤11.50.

When any one of the following conditions is further met, it helps reducethe total length of the optical imaging lens set without overlycompromising the telescopic function.TTL/T ₂≤22.8;ALT/T ₄≤8.60;TTL/(G ₂₃ +G ₄₅)≤8.50;TTL/(T ₄ +T ₅)≤6.50;(T ₁ +T ₄)/T₂≤4.50.

It is preferably:10.50≤TTL/T ₂≤22.8;5.60≤ALT/T ₄≤8.60;4.20≤TTL/(G ₂₃ +G ₄₅)≤8.50;5.30≤TTL/(T ₄ +T ₅)≤6.50;2.80≤(T ₁ +T4) /T₂≤4.50;to overly increase the total length of the optical imaging lens set whenthe telescopic function is overly enhanced.

With respect to:EFL/(G ₁₂ +G ₂₃)≤12.70;EFL/(G ₂₃ +G ₄₅)≤8.60;EFL/(G ₁₂ +G ₂₃ +G ₄₅)≤10.50;EFL/T ₅≤11.80;EFL/G ₃₄≤12.50;by limiting the relationship amongst EFL, the length thickness and theair gaps, it helps enhance the telescopic function without compromisingthe imaging quality. It is preferably:5.80≤EFL/(G ₁₂ +G ₂₃)≤12.70;4.60≤EFL/(G ₂₃ +G ₄₅)≤8.60;4.50≤EFL/(G ₁₂ +G ₂₃ +G ₄₅)≤10.50;8.5≤EFL/T ₅≤11.80;3.70≤EFL/G ₃₄≤12.50,in order to keep each thickness of the lens element and each air gap inpreferred ranges. A good ratio helps to control the lens thickness orthe air gaps to maintain a suitable range and keeps a lens element frombeing too thick to facilitate the reduction of the overall size or toothin to assemble the optical imaging lens set.

With respect to:5.5≤ALT/(G ₁₂ +G ₄₅);6.5≤ALT/T ₂;4.2≤TTL/(G ₁₂ +G ₂₃ +G ₄₅);4.2≤ALT/(T ₂ +T ₃);1.3≤ALT/G ₃₄;4.0≤TTL/(T ₁ +T ₂);3.20≤TTL/(G ₁₂ +G ₃₄);9.50≤EFL/(T ₂ +T ₄);it is preferably:5.5≤ALT/(G ₁₂ +G ₄₅)≤22.90;6.5≤ALT/T ₂≤9.50;4.2≤TTL/(G ₁₂ +G ₂₃ +G ₄₅)≤8.0;4.2≤ALT/(T ₂ +T ₃)≤4.60;1.3≤ALT/G ₃₄≤1.90;4.0≤TTL/(T ₁ +T ₂)≤5.80;3.20≤TTL/(G ₁₂ +G ₃₄)≤4.30;9.50≤EFL/(T ₂ +T ₄)≤11.50in order to keep each thickness of the lens element and each air gap inpreferred ranges, good ratio helps to control the lens thickness or theair gaps to maintain a suitable range and keeps a lens element frombeing too thick to facilitate the reduction of the overall size or toothin to assemble the optical imaging lens set.

The above limitations may be properly combined at the discretion ofpersons who practice the present invention and they are not limited asshown above. In the light of the unpredictability of the optical imaginglens set, the present invention suggests the above principles toappropriately reduce the length of the lens element set, to have betterF number, to have better imaging quality or to have better assemblingyield to overcome the shortcomings of prior art.

The above-mentioned one or more conditions may be properly combined inthe embodiments. In addition to the above ratios, the curvatures of eachlens element or multiple lens elements may be fine-tuned to result inmore fine structures to enhance the performance or the resolution. Forexample, the first object-side surface 11 of the first lens element 10may additionally have a convex part in the vicinity of the optical axis.The above limitations may be properly combined in the embodimentswithout causing inconsistency.

In each one of the above examples, the longitudinal sphericalaberration, the astigmatic aberration and the distortion aberration meetrequirements in use. By observing three representative wavelengths ofred, green and blue, it is suggested that all curves of every wavelengthare close to one another, which reveals off-axis light of differentheights of every wavelength all concentrates on the image plane, anddeviations of every curve also reveal that off-axis light of differentheights are well controlled so the examples do improve the sphericalaberration, the astigmatic aberration and the distortion aberration. Inaddition, by observing the imaging quality data the distances amongstthe three representing different wavelengths are pretty close to oneanother, which means the present invention is able to concentrate lightof the three representing different wavelengths so that the aberrationis greatly improved. Given the above, the present invention providesoutstanding imaging quality by the above designs of each lens element aswell as the excellent synergies gained from the combinations of lenselements.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. An optical imaging lens set, from an object sidetoward an image side in order along an optical axis, comprising: a firstlens element, a second lens element, a third lens element, a fourth lenselement and a fifth lens element, said first lens element to said fifthlens element each having an object-side surface facing toward saidobject side as well as an image-side surface facing toward said imageside, wherein: said first lens element has an image-side surface with aconcave portion in a vicinity of its periphery and with a concaveportion in a vicinity of said optical axis; said second lens element isof a plastic material; said third lens element has an object-sidesurface with a concave portion in a vicinity of said optical axis and animage-side surface with a concave portion in a vicinity of itsperiphery; said fourth lens element has an object-side surface with aconcave portion in a vicinity of said optical axis; and said fifth lenselement has an object-side surface with a concave portion in a vicinityof its periphery and an image-side surface with a convex portion in avicinity of said optical axis, and the optical imaging lens setexclusively has five lens elements with refractive power, EFL is aneffective focal length of said optical imaging lens set, said secondlens element has a second lens element thickness T₂ along said opticalaxis and said fourth lens element has a fourth lens element thickness T₄along said optical axis to satisfy 9.50≤EFL/(T₂+T₄).
 2. The opticalimaging lens set of claim 1, wherein TTL is a distance from said firstobject-side surface of said first lens element to an image plane alongsaid optical axis to satisfy 10.50≤TTL/T₂≤22.80.
 3. The optical imaginglens set of claim 2, wherein ALT is a total thickness of all five lenselements along said optical axis, an air gap G₁₂ between said first lenselement and said second lens element along said optical axis and an airgap G₄₅ between said fourth lens element and said fifth lens elementalong said optical axis to satisfy5.50≤ALT/(G₁₂+G₄₅).
 4. The opticalimaging lens set of claim 1, wherein ALT is a total thickness of allfive lens elements along said optical axis to satisfy 6.50≤ALT/T₂. 5.The optical imaging lens set of claim 4, wherein TTL is a distance fromsaid first object-side surface of said first lens element to an imageplane along said optical axis, an air gap G₁₂ between said first lenselement and said second lens element along said optical axis, an air gapG₂₃ between said second lens element and said third lens element alongsaid optical axis and an air gap G₄₅ between said fourth lens elementand said fifth lens element along said optical axis to satisfy4.20≤TTL/(G₁₂+G₂₃+G₄₅).
 6. The optical imaging lens set of claim 1,wherein ALT is a total thickness of all five lens elements along saidoptical axis to satisfy ALT/T₄≤8.60.
 7. The optical imaging lens set ofclaim 6, wherein TTL is a distance from said first object-side surfaceof said first lens element to an image plane along said optical axis, anair gap G₂₃ between said second lens element and said third lens elementalong said optical axis and an air gap G₄₅ between said fourth lenselement and said fifth lens element along said optical axis to satisfy4.20≤TTL/(G₂₃+G₄₅)≤8.50.
 8. The optical imaging lens set of claim 1,wherein an air gap G₁₂ between said first lens element and said secondlens element along said optical axis and an air gap G₂₃ between saidsecond lens element and said third lens element along said optical axisto satisfy EFL/(G₁₂+G₂₃)≤12.70.
 9. The optical imaging lens set of claim8, wherein TTL is a distance from said first object-side surface of saidfirst lens element to an image plane along said optical axis and saidfifth lens element has a fifth lens element thickness T₅ along saidoptical axis to satisfy TTL/(T₄+T₅)≤6.50.
 10. The optical imaging lensset of claim 1, wherein an air gap G₂₃ between said second lens elementand said third lens element along said optical axis and an air gap G₄₅between said fourth lens element and said fifth lens element along saidoptical axis to satisfy EFL/(G₂₃+G₄₅)≤8.6.
 11. The optical imaging lensset of claim 10, wherein ALT is a total thickness of all five lenselements along said optical axis and said third lens element has a thirdlens element thickness T₃ along said optical axis to satisfy4.20≤ALT/(T₂+T₃).
 12. The optical imaging lens set of claim 1, whereinsaid first lens element has a first lens element thickness T₁ along saidoptical axis to satisfy 2.80≤(T₁+T₄)/T₂≤4.50.
 13. The optical imaginglens set of claim 12, wherein an air gap G₁₂ between said first lenselement and said second lens element along said optical axis, an air gapG₂₃ between said second lens element and said third lens element alongsaid optical axis and an air gap G₄₅ between said fourth lens elementand said fifth lens element along said optical axis to satisfyEFL/(G₁₂+G₂₃+G₄₅)≤10.50.
 14. The optical imaging lens set of claim 1,wherein ALT is a total thickness of all five lens elements along saidoptical axis and an air gap G₃₄ between said third lens element and saidfourth lens element along said optical axis to satisfy 1.3≤ALT/G₃₄. 15.The optical imaging lens set of claim 14, wherein said fifth lenselement has a fifth lens element thickness T₅ along said optical axis tosatisfy 8.50≤EFL/T₅≤11.80.
 16. The optical imaging lens set of claim 1,wherein an air gap G₃₄ between said third lens element and said fourthlens element along said optical axis to satisfy 3.70≤EFL/G₃₄≤12.50. 17.The optical imaging lens set of claim 16, wherein TTL is a distance fromsaid first object-side surface of said first lens element to an imageplane along said optical axis, said first lens element has a first lenselement thickness T₁ along said optical axis to satisfy4.00≤TTL/(T₁+T₂).
 18. The optical imaging lens set of claim 1, whereinTTL is a distance from said first object-side surface of said first lenselement to an image plane along said optical axis, an air gap G₁₂between said first lens element and said second lens element along saidoptical axis and an air gap G₃₄ between said third lens element and saidfourth lens element along said optical axis to satisfy3.20≤TTL/(G₁₂+G₃₄).